Modern automotive fuel tanks are designed to hold a quantity of fuel and maintain a volume of vapor above the fuel. Because fuels are highly volatile, a portion of the fuel vaporizes and forms a fuel vapor mixture in the fuel tank. During refueling, this fuel vapor mixture must be displaced by fuel. To prevent the unwanted release of the fuel vapor into the atmosphere, various means exist to remove the fuel from the vapor. Typical of these systems is an adsorbent taught in U.S. Pat. No. 3,831,353 where a fuel tank is connected to a canister containing an adsorbent such as activated carbon. Fuel in the fuel vapor passes through the canister and is trapped by the adsorbent. The adsorbent is purged by drawing air from the air induction system of the engine. Carbon canisters of this type require a relatively large volume of space to trap fuel vapor and connection lines between the fuel tank, canister and engine. The bulk and complexity of conventional canister systems as well as the possibility of permeation makes an in-tank vapor recovery system desirable.
Thermal electric coolers have been used to alternatively heat and cool absorbers, fuels and fuel vapors. To date, they have not provided an efficient, compact design specifically directed to reducing the quantity of fuel vapor above a liquid.